Accidents in House

Question
My 71/2  year old mixed breed dog has started peeing on the carpet.  I took him to the vet and was given antibiotics after he went twice near the door he usually goes out, and was drinking excessively.  However, after the meds he stopped drinking too much but has now gone on the carpet twice more in different spots in the middle of the same room.  I have gone so far as to replace the padding under the carpet where he went the first two times, and have saturated the other two spots with "Natures Miracle". Why would a dog who has been house trained for so long start going in the house?  I almost get the feeling he just doesn't want to go out on his runner by himself and would rather go inside. He usally gets one 20 minute walk at night and he will mark in several places along the way and usually poops once.  He is let out in the morning, then btw.1-3pm and then around 5-7pm and then we walk btw. 8-10pm.  He has always tried to be the boss, but I have done a lot to not let him:  make him walk behind me, make him wait to go in the door after me, make him come to me on command etc.  Any ideas?

Answer
Hi Stephanie;
No doubt the meds are making him feel different, and he may just have to go more often.
The doctor may need to be re-visited, in case he has a continued Kidney infection, or reaction from the medicines...I would give your Vet a call and have a follow up done on him.
He may have "Incontinence" as well...
So, you may be forced to crate him when you are not with him all the time...and also take him out a bit more often.
I think if you go to your Vet first, then you will find out a whole lot more!
Thank you for asking me your question, and I would love to assist you further...Let me know how it goes.
And please do send your feedback to the website!
Best wishes,
Melissa